Yes, Devil's Lake in Wisconsin is swimmable. Devil's Lake State Park, located near Baraboo, Wisconsin, offers two large sandy beaches on the north and south shores of the lake. The clear waters and sandy bottom make it a popular spot for swimming during the warmer months. Lifeguards are not provided, so swimming is at your own risk. Additionally, there are designated swimming areas marked by buoys to ensure a safe and enjoyable experience for swimmers.